1. Field of the Invention
The present invention relates to a concrete-mortar transfer system of a concrete pump car in which the concrete transfer system is mounted to the concrete pump car for transferring the mortar concrete to a placing position at a construction job-site and when increasing/decreasing the transfer distance of the concrete, a work for separating or changing the concrete pump car is not required, thereby selectively capable of transferring the concrete with a high or a low pressure by a simple operation.
2. Description of the Background Art
Generally, a pump car is an equipment for transferring the fluent mortar concrete to the placing position of the concrete and includes a transfer system for transferring the mortar concrete(hereinafter, referred as concrete) with pressure. The transfer system sucks the concrete inputted to a hopper from a ready-mixed concrete car and thereafter transfers it to the placing position by an operation of a piston through a transfer tube mounted up to the placing position. Also, a boom apparatus for leading the transfer tube for transferring the concrete up to a high position may be selectively mounted to the pump car.
Also, FIG. 1 is an outline plane view for explaining a concrete transfer system of a concrete pump car in accordance with a conventional art and FIG. 2 is an oil pressure circuit diagram for simply showing a concrete transfer system of a concrete pump car in accordance with a conventional art. As shown in FIGS. 1 and 2, the concrete transfer system comprises a pair of concrete input tubes 20 and 30 mounted in union to communication holes punched to the inside surface of the hopper 10 on which an agitator 12 worked by the power of an engine is mounted, drive cylinders 40 and 50 mounted on the same lines of the concrete input tubes 20 and 30 for sucking and transferring the concrete by forward and backward movements of pressure pistons 44 and 54 mounted to rod ends 42 and 52, an oil pressure apparatus including an oil pressure pump, various control valves and an oil pressure hose for driving the drive cylinders and simultaneously controlling their driving operations.
A swing valve 14 is mounted between communication holes of the concrete input tubes 20 and 30 and a discharge hole of a transfer tube 16a and performs a swing operation for communicating alternately it to both communication holes, and when advancing the rod, the concrete discharged from the concrete input tubes 20 and 30 can be transferred to the transfer tube 16.
On the other hand, the concrete transfer system in accordance with the conventional art will be described as follows. As shown in FIG. 2, the drive cylinder comprises a first drive cylinder 40 and a second drive cylinder 50, inside pistons b of the first and second drive cylinders 40 and 50 are connected with each other by a connection oil pressure line 66, a rod side a of the first drive cylinder 40 and a side of an oil pressure pump 60 are connected with each other by a first supply line 62, and a rod side a of the second drive cylinder 50 and the other side of the oil pressure pump 60 are connected with each other by a second supply line 64.
The oil pressure pump 60 comprises an oil path change drive unit 70 for capable of changing the flow direction of the fluid pumped and transferred into a side or the other side. The oil path change drive unit 70 can be constructed variously by an oil pressure type or an electric type and generally it is constructed by the oil pressure type. The oil pressure change drive unit is well-known in the art, its detailed explanation and the drawing will be omitted.
The oil path change drive unit 70 is operated by the control signal of a control unit 80, thereby transferring the fluid to the rod side a of a first drive cylinder 40 or a second drive cylinder 50. The control signal applied to the oil path change drive unit 70 by the control unit 80 is produced as follows; as shown in FIG. 1, when a rod sensing sensor 90 mounted on a connection box(a water box) 100, which is mounted between the concrete input tubes 20 and 30 and the body unit of the drive cylinder, senses the movement of the rod, the control unit 80 receives the sensing signal from the rod sensing sensor 90 and produces the control signal.
More specifically, two rod sensing sensor 90 are installed to an upper portion of a rod movement path of the connection box 100 for sensing the movement of the rods 42 and 52 of the first drive cylinder 40 and the second drive cylinder 50, sense a sensing block 51 interlocked when moving the rods and applies a sensing signal to the control unit 80. For example, as shown in FIGS. 1 and 2, when oil pressure is supplied to a rod side a of the first drive cylinder 40, the rod is moved backwardly and the concrete is sucked into the inside of the concrete input tube 20. Also, when a piston of the first drive cylinder 40 is moved backwardly, the fluid at the front of the piston is inputted to a piston side b of the second drive cylinder 50 through a connection oil pressure line 66. Accordingly, the rod of the second drive cylinder 50 is advanced and pushed ahead the concrete filled on the concrete input tube 30 in the front of the rod. At this time, a swing valve 14 is communicated with the communication hole of the concrete input tube 30 by a predetermined operation, thereby transferring the concrete to the transfer tube 16.
In the process as above, when the rod of the first drive cylinder 40 is moved backwardly completely, the sensing block 41 installed to an end side of the rod is sensed by the rod sensing sensor 90 and the state that a backward movement of the first drive cylinder 40 is completed is applied to the control unit 80. Accordingly, the control unit 80 applies a control signal to an oil path change drive unit 70, thereby supplying the fluid pumped by the oil pressure pump 60 to the rod side a of the second drive cylinder 50 through a second supply line 64, and then the rod of the second drive cylinder 50 is moved backwardly, so that the concrete is sucked to the concrete input tube 30. The fluid within the inside of the piston is inputted to the inside of the first drive cylinder 40 through the connection oil pressure line 66 and then the piston is pushed out, so that the rod of the first drive cylinder 40 is advanced and pushed ahead the concrete filled on the concrete input tube 20 in the front of the rod, thereby transferring the concrete to the transfer tube 16.
Also, in the above process, when the rod of the second drive cylinder 50 is completely moved backwardly, the sensing block 51 installed at an end side of the rod is again sensed by the rod sensing sensor 90 and the state that a backward movement of the first drive cylinder 50 is completed is applied to the control unit 80, the control unit 80 applies a control signal to an oil path change drive unit 70, thereby repeating the above operation.
On the other hand, the concrete transfer system of the concrete pump car sucks the concrete of a hopper of a ready-mixed concrete car and thereafter transfers the concrete to a placing position by an operation of the piston. When the transfer distance is determined, a boom apparatus having a predetermined length of a transfer tube is constructed by the pump car, however, since the height of the building is variable, there is needed a concrete transfer system having a proper transfer distance.
However, in the conventional concrete transfer system as shown in FIG. 2, oil with a constant pressure is always supplied to a rod side a of the drive cylinder from the oil pressure pump 60, so that the force for advancing the piston by the fluid inputted to the inside of the cylinder is comparatively weaker (than the structure that the fluid is inputted to the piston side of the drive cylinder), so that it is only possible to transfer the concrete with a short distance. The reason, as well known in the art, is that the force applied to the rod side for sucking or discharging the concrete is proportional to the unit area where the oil pressure is worked. Accordingly, because the unit area of the piston at the rode side is smaller than the inside area of the cylinder piston, in the conventional concrete transfer system, because the fluid(oil pressure oil) is only always supplied to the rod side, the force applied to the rod is weak, accordingly, the force of the pressure pistons 44 and 54 for performing a sucking and discharging operation within the concrete input tube become weak, so that there is a disadvantage that it can be only used for transferring a short distance.
Also, as shown in FIG. 2, in the conventional concrete transfer system of the concrete pump car, for increasing the transfer distance of the concrete, when the position for supplying the fluid from the oil pressure pump 60 to the inside of the cylinder is changed to the piston side b of the cylinder, respectively, the transfer distance of the concrete can be increased. However, at this time, there are several problems that since each oil horse must be separated and assembled by exchanging with the combining positions, so that the working is very difficult and it is required much time in the exchanging work. Also, since various devices are mounted to the concrete transfer system, it is difficult to separate and assemble the devices in the narrow places.
In addition, since the length of the drive cylinder is very long and all oil pressure horses also must be formed very long for changing the connection positions of the oil pressure horses, the concrete transfer system become very complex and it is difficult to mount the system to the pump car. Especially, when the oil pressure horses are separated for changing the connection positions, the pressure oil is discharged, so that when the oil must not be injected again after assembling, the device dose not work in proper. Also, there may be occurred a contamination of the pump car or a serious environment contamination due to the oil leaked at the circumference.